The present invention pertains to an interlocking closure device, and, more particularly, to a closure device with a slider. The closure device of the present invention may be employed in traditional fastener areas, and is particularly suited for use as a fastener for storage containers, such as plastic bags.
The use of fastening devices for the closure of containers, including plastic bag bodies, is generally known. Furthermore, the manufacture of fastening devices made of plastic materials is generally known to those skilled in the art relating to closure devices, as demonstrated by the numerous patents in this area.
A particularly well-known use for fastening devices is in connection with flexible containers, such as bag bodies. The closure device and the associated container may be formed from thermoplastic materials, and the closure device and sidewalls of the container can be integrally formed by extrusion as a single piece. Alternatively, the closure device and sidewalls may be formed as separate pieces and then connected by heat sealing or any other suitable connecting process. The closure devices when incorporated as fasteners on bag bodies have been particularly useful in providing a closure means for retaining the contents within the bag body.
Conventional closure devices utilize mating male and female closure elements which are occluded. When conventional closure devices are employed, it often is difficult to determine when the male and female closure elements are occluded. This problem is particularly acute when the closure devices are relatively narrow. Accordingly, when conventional closure devices are employed, there exists a reasonable likelihood that the closure device is at least partially open.
The occlusion problem arises from the inability of a user to perceive when the male and female closure are occluded to form a seal between the contents of the bag and the environment external to the bag. A number of solutions to this problem have been attempted. For example, U.S. Pat. Nos. 4,186,786, 4,285,105, and 4,829,641, as well as in Japanese patent application No. 51-27719, disclose fasteners that provide a visual indication that the male and female closure elements are properly occluded. Specifically, a color change means for verifying the occlusion of the male and female members of the closure is provided wherein male and female members having different colors are employed, and, upon occlusion, provide yet a different color. For example, the female member of the closure may be opaque yellow and the male member of the closure may be translucent blue. Upon occlusion of the male member and female member a composite color with a green hue results. This use of a color change greatly improves the ability of the user of the interlocking closure device to determine when the male and female members are occluded.
The change in color that is viewed when dissimilarly colored male and female members are occluded is demonstrated in a commercially available product sold under the trademark GLAD-LOCK (Glad-Lock is the registered trademark of First Brands Properties, Inc., Danbury, Conn. United States of America). This color change effect may be enhanced by the incorporation of a color change enhancement member in the closure device, as disclosed in U.S. Pat. No. 4,829,641.
Color-changing closure devices are not a universal solution to the aforementioned problem of assuring full closure, however. For example, the color-change effect is imperceptible in the dark, thus mooting the color-change advantage of the closure devices when they are used under such conditions. In addition, sight-impaired or color-blind people may not be able to perceive the color-change effect. Accordingly, it would be desirable to provide a closure device that affords other indications of occlusion.
The prior art has attempted to furnish a fastener that provides a tactile or audible indication of occlusion. For example, U.S. Pat. Nos. 4,736,496, 5,138,750, 5,140,727, 5,403,094, and 5,405,478, as well as EP 510,797, disclose closure devices that allegedly provide a tactually or audibly perceptive indication of proper interlocking of the closure elements. It is said that, upon occlusion of the disclosed closure devices, a user is able to feel or hear that full closure is accomplished. For example, U.S. Pat. No. 4,736,946 discloses the use of additional ribs on either side of the closure elements. These ribs are said to give an improved xe2x80x9cfeelxe2x80x9d to the closure, thus aiding a user in aligning the closure elements.
Such devices are difficult to handle by individuals who have limited manual dexterity. Thus, in order to assist these individuals and for ease of use by individuals with normal dexterity, the prior art has attempted to furnish a fastener that provides a reclosable fastener and a slider for opening and closing the fastener. For example, several U.S. Patents disclose fasteners with sliders. However many of these fasteners use either: (1) a separator finger which extends between the closure elements, such as U.S. Pat. Nos. 3,054,434, 3,115,689, 3,122,807, 3,230,593, 3,426,396, 3,713,923, 4,199,845, 4,262,395, 5,007,142, and 5,010,627 (FIGS. 9 and 10); or (2) the separator finger runs along a track above the closure elements, such as, U.S. Pat. Nos. 5,007,143, 5,010,627 (FIGS. 3-8), 5,020,194, 5,067,208, 5,070,583, 5,088,971, 5,131,121, 5,161,286, 5,283,932, 5,301,395, 5,426,830, 5,442,837 and 5,448,808.
With respect to fasteners which use a separator finger which extends between the closure elements, these fasteners do not provide a leak proof seal because the separator finger extends between the closure elements. With respect to the fasteners which run along a track, the fastener typically include slits, notches or another means to accommodate the separator finger in the end position. These means are used to achieve occlusion of the closure elements at the end position and thus attempt to achieve a leak proof seal. For example, U.S. Pat. Nos. 5,020,194, 5,067,208, 5,088,971, 5,131,121, 5,161,286, 5,301,394, 5,301,395, and 5,442,837 use a slit, notch or other means to accommodate the separator finger in the end position. These means in the fasteners create additional steps in the manufacturing process and thus may increase the cost of these fasteners.
A reclosable fastener with a slider and without a separator finger nor the use of a track is described in U.S. Pat. Nos. 3,074,137 and 5,442,838. However, the fastener in the ""137 patent would be too expensive to manufacture and may not seal when the slider is in the end position. With respect to the fastener in the ""838 patent, the slider does not manipulate the interlocking elements directly. Rather, the slider engages the structure located below the interlocking elements to control the opening and closing of the interlocking elements. Difficulties and additional variables can arise when the slider does not act directly upon the interlocking elements. In addition, the fastener in the ""838 patent may not operate properly if the tolerances are incorrect for the slider and/or the fastener. The structure below the interlocking elements and/or the slider may be difficult to extrude or manufacture. If the tolerances are incorrect, the slider may not move smoothly or fail to open or close the fastener elements. Thus, it would be difficult to achieve a properly functioning fastener.
In addition, the prior art closure devices are designed to deocclude if a sufficient force is applied laterally to the closure device. Thus, the closure device may unintentionally deocclude if a force is applied laterally. For example, when the closure device is used on a plastic bag and the contents of the bag exert a force on the bag sidewalls, then the closure device may unintentionally deocclude.
Furthermore, as noted above, several closure devices use a slider which includes: (1) a separator finger; or (2) a separator finger and a track. These sliders can be expensive to manufacture and assemble onto the fastening strips.
Thus, the prior art has failed to afford a closure device with a slider which occludes and deoccludes by using a shearing action. Specifically, the prior art has failed to show a closure device in which the first fastening strip is sheared relative to the second fastening strip. For example, if the longitudinal axis of the fastening strip is the X axis, the width is the Y axis and the height is the Z axis, then the prior art has failed to disclose a closure device which occludes in the Z axis.
It is a general object of the present invention to provide a closure device wherein the opening and closing force is applied in shear as opposed to lateral or rolling.
An additional object is to provide a closure device so that the opening and closing forces are applied only to one of the fastening strips while the other fastening strip is held stationary. This situation can simplify the design of a slider.
Another object is to provide a slider for use in conjunction with a shear closure which does not require a separator finger to open or close the fastening strips.
A further object is to provide a slider for use in conjunction with a shear closure which does not require special flanges designed into the fastening strips that are to be gripped by the slider to open the fastening strips.
Another object is to provide a slider which can be installed around the fastening strips without opening or closing the fastening strips.
An additional object of the invention is to provide fastening strips with profiles having a combination of pivoting forces and shearing forces that can take advantage of the attributes of the shearing action.
A further object is to provide a closure device wherein the force applied to the first fastening strip could also push the second fastening strip away and apart from the first fastening strip.
Another object is to provide a closure device wherein the closure device maintains a leak proof seal for a considerable amount of the distance during the opening and closing of the closure device.
It is a further general object of the present invention to provide a container that is closeable and sealable by means of such a closure device.
The present invention satisfies these general objects by providing a closure device with interlocking fastening strips wherein the fastening strips occlude and deocclude in the Z axis by using a shearing action. The closure device comprises first and second interlocking fastening strips arranged to be interlocked over a predetermined length. The fastening strips have a longitudinal X axis and a transverse Y axis which is perpendicular to the longitudinal X axis. The fastening strips have a vertical Z axis which is perpendicular to the longitudinal X axis and which is perpendicular to the transverse Y axis. The fastening strips are occluded and deoccluded by moving one fastening strip relative to the other fastening strip in substantially the vertical Z axis.
During occlusion and deocclusion, portions of the fastening strips may rotate, deflect and/or move in the transverse Y axis. In addition, the fastening strips may include a locking feature which assists in preventing unintentional deocclusion of the closure device.
The closure device may also include a slider which slidably engages said first and second fastening strips. The slider facilitates the occlusion of the fastening strips when moved towards a first end of the fastening strips and deocclusion of the fastening strips when moved towards a second end of the fastening strips.